1. Field of the Invention
The present invention relates to a planar light source device and a liquid crystal display (LCD) device having the planar light source device. More particularly, the present invention relates to a field emission-type planar light source device, and an LCD device having the planar light source device.
2. Description of the Related Art
Various flat display panel devices, such as liquid crystal display (LCD) devices, plasma display panel (PDP) devices, organic light-emitting diode (OLED) devices, etc., have been developed to replace cathode ray tube (CRT) devices.
The LCD device that is widely used in various fields includes an LCD panel that has a thin-film transistor (TFT) substrate, a color filter substrate, and a liquid crystal layer interposed between the TFT substrate and the color filter substrate. The LCD panel is a non-emissive-type display element, and thus the LCD device requires a backlight unit that is disposed under the TFT substrate to supply the LCD panel with light. A liquid crystal of the liquid crystal layer varies arrangement in response to an electric field applied thereto, and thus a light transmittance of the liquid crystal layer is changed, thereby displaying an image having a predetermined gray-scale.
A light source of the backlight unit includes a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a flat fluorescent lamp (FFL) that is a type of planar light source, etc. Each of the CCFL, EEFL, and FFL generates light using a plasma discharge. When a high voltage difference is applied to electrodes of the lamp, an electric field is formed between the electrodes to emit electrons. The electrons excite mercury molecules, and ultraviolet light is generated from the excited mercury molecules. A fluorescent layer changes the ultraviolet light into visible light so that the visible light exits the lamp. However, mercury is a pollutant and is restricted by environmental regulations. Thus, a light source that does not use mercury is required.